In recent years, attention has been increasingly paid to a display and a lighting device which use an OLED light-emitting element. Each of the OLED devices has a structure in which an organic light-emitting element is sandwiched by substrates (glass sheets) on which a transparent conductive film such as an ITO or FTO film is formed (see, for example, Patent Literature 1). When an electric current flows through the organic light-emitting element in this structure, a hole and an electron in the organic light-emitting element are combined to emit light. The emitted light enters a glass sheet via the transparent conductive film and is released out while repeating reflection in the glass sheet.